External HR strap + Buzz impact on battery life

I have a 50 mile hill race coming up in April. I'm wondering if my watch will last the distance. I expect to do it in 7.5-8hrs.

Last night I left the watch in an upstairs window (good gps signal) and recorded a "run". It lasted for 8hr50m before running out.

I'd like to wear the tomtom external Heart rate monitor strap if poss during the race - I'm hopeless at running slow enough in long races, so want to check my HR up hills.

So I could do another test where the external strap is linked to check impact on battery life. But my question is really, what if the strap is not attached to a person.... Will the battery drain be any different lying on the window ledge to actually running with it on? Perhaps because it's constantly trying to find a heart.

What settings do I need to set for optimal battery life? Anything I've forgotten?
Sync to OFF.
Goals to OFF.

Also does anyone have any idea how much "Buzz" impacts battery life? It would cool if I could set it to buzz every 20 mins to remind me to sip water.

Comments

The external strap will not have a major impact on battery life as it is passively collecting data, but the internal certainly will. Same goes for buzz as the vibration motor and backlight are major energy draws. 7-8 hours is certainly feasible, it can theoretically get up to 10 (by the way 50 miles in 7-8 hours is impressive!). Turn off any training modes, do not use trails mode, turn off the phone sync (may even want to factory reset it so there is not even a phone connected just in case), turn off the internal HR, turn off the activity tracker, do not use the backlight and touch the device as little as possible. Changing screens a lot will draw more battery as it has to constantly redraw them. Best to just get the display to the metrics you want and leave it alone.

I hope this helped answer your question. If so, please mark it as a solution so others can look for it if they have the same question.

That's all really useful, especially about changing screens. So glad I asked. Thanks.

Wish there was a 6 field mode so lots of data same size as the bottom 2. I need HR, pace and choose one other from time elapsed or distance. Not sure what I'd choose. Probably distance. I could always wear a normal stop watch on the other wrist

It should be at the bottom right next to Like or Quote. If not, don't worry about it a moderator will fix it.

As to the screens they have stuck with the same screen layout for 5 years and are not going to change it now that they have left the wearables market and are no longer producing devices. It is what it is and we will have to live with it.